#include<iostream>
#include<vector>
using namespace std;

int longestCommonSubsequence(string s1, string s2) {
    int m = s1.size(), n = s2.size();
    vector<vector<int>>dp(m + 1, vector<int>(n + 1));

    for (int i = 1; i <= m; i++)
    {
        for (int j = 1; j <= n; j++)
        {
            if (s1[i - 1] == s2[j - 1]) dp[i][j] = dp[i - 1][j - 1] + 1;
            else dp[i][j] = max(dp[i - 1][j], dp[i][j - 1]);
        }
    }

    return dp[m][n];
}

int main()
{
    cout << longestCommonSubsequence("acdef","defa") << endl;
    return 0;
}